%% Image selected per Image Pickin' thread: http://tvtropes.org/pmwiki/posts.php?discussion=1465726962064759100%% Please do not replace or remove without starting a new thread.%%[[quoteright:285:[[WesternAnimation/TheSimpsons http://static.tvtropes.org/pmwiki/pub/images/homer_simpson_butterfly_effect.png]]]] [-[[caption-width-right:285:[[SpaceWhaleAesop Remember, kids: don't sneeze on dinosaurs, unless you want your neighbor to be Big Brother]].]]-]

->''"Don't do anything, don't ''touch'' anything, Sci-fi rule number 1: you start messing with the past, you end up with monkeys ruling the future."''-->-- '''Cyborg''', ''WesternAnimation/TeenTitans''%%%% One quote is sufficient. Please place additional entries on the quotes tab.%%

Want to [[TimeTravel go back in time]] to stop your parents from losing their retirement money in the Dotcom crash? Save a loved one from a fatal accident? Nudge a closet a little to the left to [[ArsonMurderAndJaywalking avoid hitting]] [[MundaneUtility your toe]]? In some universes, you're not just going to run into YouCantFightFate, but into FinaglesLaw on a grand scale: the Butterfly of Doom. Any and every change made in the past will ''always'' have an unintended and horrible side effect.

Much like a temporal [[BeCarefulWhatYouWishFor Monkey's Paw]], you might succeed at changing the thing you intended, but at a terrible cost. Telling your parents to move their money elsewhere gets them arrested for insider trading; the loved one you saved develops a wasting terminal cancer; the closet you moved is now on a weak floorboard and crashes through it, destroying your house. To repair the damage, it's usually necessary to travel in time again to SetRightWhatOnceWentWrong -- more specifically, to set right what ''you'' made go wrong.

A FantasticAesop, the Butterfly of Doom is intended to drive home that any attempt to change history will be met with the wrath of Fate itself. As a subtrope of ForWantOfANail, it can overlap with ItsAWonderfulPlot, in which the butterfly is you. GodwinsLawOfTimeTravel is a subtrope in which the thing that you change leads to Hitler winning UsefulNotes/WorldWarII.

This is one of the techniques that writers use to ensure that TimeTravel doesn't interfere with StatusQuoIsGod. Others are that TimeTravel creates {{Alternate Universe}}s, that creating a TemporalParadox [[TimeCrash obliterates reality]] or unleashes the ClockRoaches to eat offenders, and that Time is resilient and [[InSpiteOfANail can absorb]] changes without breaking.

See also FinaglesLaw, HitlersTimeTravelExemptionAct, SchrodingersButterfly, RubeGoldbergDevice, RubeGoldbergHatesYourGuts, NecroNonSequitur, ForWantOfANail and RippleEffectProofMemory. Contrast SaveThisPersonSaveTheWorld and MergedReality. Unrelated to ButterflyOfTransformation or its subtropes.

NotToBeConfusedWith another common trope resulting from the [[https://en.wikipedia.org/wiki/Butterfly_effect Butterfly Effect]], DisasterDominoes, where a small accident or event sets off a whole chain of increasingly destructive events.

----!!Examples:

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[[folder:Anime & Manga]]* Almost the entire point of all events in ''Manga/XxxHolic''. Interesting that Yuuko's symbol is the butterfly, though that falls under [[ButterflyOfDeathAndRebirth another butterfly trope]].* In an episode of ''Manga/PenguinMusume'', Kujira learns that she confessed her love to Sakura when they were both young girls (Kujira was raised as a boy.) Embarrassed into action, Kujira takes the Time-Penguin-X1 (yeah, you heard me) back to prevent herself from confessing. After older-Kujira realizes she's made a horrid mess, she works to repair the timeline, causing her younger self to instead make a marriage vow. HilarityEnsues.* ''Anime/TheGirlWhoLeaptThroughTime''. Though Makoto never tries to change anything particularly big (she uses it for stuff like repeating a karaoke session over and over for several hours), once or twice she changes something small that has massive and unexpected repercussions. After several failed attempts at matching a friend with a girl who who likes him by leaping back in time, she finally gets it right. [[spoiler:He borrows Makoto's bike, the brakes snap and both he and the girl die in a train accident that Makoto herself only narrowly avoided earlier. Fortunately, Chiaki was around to fix things.]]* Perhaps not even needing a mention, ''VisualNovel/SteinsGate'' relies much on the butterfly effect theory. In fact the visual novel (and anime to a lesser extent) analyze much of the science after everything had GoneHorriblyWrong.* This is practically the premise of ''Ore ga Doutei wo Sutetara Shinu Ken ni Tsuite'' (''How I'll die if I lose my virginity'') where the protagonist goes back in time after his best friend kills him when he was 32 years old.* In ''Manga/FairyTail'', this is the Defense Minister's argument against using the Eclipse Gate [[spoiler:to travel back in time to kill Zeref.]] Since [[spoiler:Zeref]] is such a huge part of their history, killing him in the past could have drastic consequences. [[spoiler:Then it was revealed to the readers later on that Zeref is the one who proposed the concept of the Eclipse Gate, meaning the plan was doomed to failure from the start and wouldn't have ended well at all]].* ''Manga/{{Berserk}}'': [[spoiler: In TheReveal, it turns out that the entire plot has been carefully constructed by the [[GodIsEvil Idea of Evil]]. It has, in its time, created demons, assemble the Godhand (its demigod-like emissaries), controlled human history and eventually shattered the boundary between fantasy and reality to disastrous effect. How? It distributed [[ArtifactOfDoom Behelits]] to ''just'' the right people at ''just'' the right times; [[HumansAreBastards human nature]] and [[TheTrainsRunOnTime the laws of physics]] ([[GambitRoulette down to the last detail]]) took care of the rest.]]* The entire Future Trunks Saga in ''Anime/DragonBallSuper'' is one big butterfly effect that messes up two timelines. [[spoiler: As Goku Black and Future Zamasu points out, it was [[NiceJobBreakingItHero Future Trunks' time traveling]] that allowed their rise since he created a timeline where Goku didn't die from the heart virus. If Goku had died, Present Zamasu would have never become interested in Goku and take his body using the Super Dragon Balls, which leads to Future Zamasu joining his past counterpart, killing the gods in every universe, and them eventually attacking Earth to punished the Earthlings for Trunks' crime]]. Even more, Goku would have never even met Zamasu if Trunks didn't return to the past again to get help fighting [[spoiler: Goku Black]], since Goku only went to U10 to see if Zamasu was Black, leading to a StableTimeLoop. [[/folder]]

[[folder:Comic Books]]* In ''ComicBook/AllStarSquadron'', the robot Mekanique is sent back from the future by the evil scientist Rotwang to prevent a car accident that will kill a small girl and a naval officer. Somehow, this change [[Film/{{Metropolis}} will prevent the rise of the rebel leader Maria in Rotwang's future who leads a slave rebellion that threatens to overthrow the ruling elite.]]* Mentioned, though not actually applicable in the ''Comicbook/{{Runaways}}'' time-travel arc:-->'''Xavin:''' As usual, you're missing the bigger issue. What you should be worried about is the ButterflyEffect.\\'''Chase:''' Dude, I'm totally on top of the Butterfly Effect! ''(aside, to Molly)'' What were they, like, bigger?* ''WesternAnimation/PinkyAndTheBrain'' (Yes, this ''is'' a comic story instead of a cartoon) once went back in time a few hours to prevent their past selves from opening a savings account at a bank that would be robbed afterwards. (They had a time machine that Brain planned to use to go to the future to get the money plus interest) When they returned to their own time, they found the world being ruled by ostriches. ([[RuleOfFunny No, really]])* ''ComicBook/{{Flashpoint}}'' involves TheFlash suddenly awakening in a CrapsackWorld and trying to figure out what caused the change to the timeline. It turns out that [[spoiler: it was all caused by TheFlash going back in time and saving his mother's life.]] Somehow this resulted in such changes as Bruce Wayne having been shot by the mugger while his parents are still alive, Franchise/WonderWoman and ComicBook/{{Aquaman}} being murderous dictators, and Frankenstein killing Hitler. ** But then averted by the ending, where [[spoiler:Pandora uses Flash in order to create a new timeline which is different but no worse than the old one ([[BrokenBase though don't ask comic fans their opinion on that]])]]* Marvel Comics' 2013 event ''Age of Ultron'' features an alternate universe in which the sentient robot Ultron has annihilated mankind and taken control of the entire planet. Wolverine goes back in time in order to kill Ultron's creator, Hank Pym, only to discover that in the new timeline, the murder of Hank Pym caused the Avengers to disband, which somehow caused Asgard to lose the Asgardian/Latverian War, which led to a present in which sorceress Morgan le Fay conquered most of Earth, and Iron Man leads a resistance of broken heroes trying to keep New York from falling into Morgan's hands. Apparently, this is worse than a universe in which humankind was completely annihilated by a sentient evil robot, as stated by the characters in the book.* In ''ComicBook/JusticeLeagueElite'', Manchester Black tries to use the reality-warper Eve to alter history so that Superman was killed before his powers developed, but she claims that there is no way for her to make such a drastic change to the universe without tearing reality itself apart.* Usually ''{{Subverted}}'' in ''ComicBook/PaperinikNewAdventures'', as time pirates are smart enough to limit themselves to steal treasures due the danger of this. That said, they ''did'' try and alter the timeline in three occasions... And every time it was somewhat 'strange':** the first time the Raider came in the present to assemble and activate a device ''made purposefully to change the timeline without risking that the alteration would backfire'';** the second time [[TheSyndicate the Organization]] sends their best agent, the aforementioned Raider, [[EnemyMine and Paperinik]] forward in time [[EvilVersusOblivion to prevent the creation of a bubble of nothingness that would erase the entire space-time continuum]]. Except that their intervention causes the experiment that would create the bubble to start early, and ''[[NiceJobBreakingItHero they personally make it go awry and nearly create the bubble]]'' (they stop it just in time). It's also implied that the Organization had already tried to stop the experiment due the risk, and their agent actually made it go awry the first time;** the third time the Organization sent the Gryphon (their best agent after [[spoiler: the Raider's death]]) in the past to neutralize Paperinik. He's successful, and somehow his actions gets the TimePolice replaced by a front of the Organization ''completely by accident'', before another intervention [[spoiler: saves the Raider and]] restores the timeline.** The reboot played it straight, with a group of [[PlanetLooters Evronians]] getting their hands on Kronin's TimeMachine and using it to prevent the creation of their enemies the Guardians of the Galaxy. Then they return to the present, and, to their horror, find out that preventing the creation of the Guardians also caused the Evronians to ''[[HeelFaceTurn become a peaceful race]]'', at which point an amused Kronin [[LampshadeHanging explains that]] ''this'' is the reason he never tried something like that.%% * In ''Comicbook/{{Seconds}}'', [[spoiler: this is the result of Katie's use of the magic mushrooms.]]* [[Comicbook/UncannyXMen Eva Bell aka Tempus]] began with the power to create localized bubbles that allow her to manipulate the passage of time, by slowing everything around her down while speeding herself up. This later developed into a full-on ability to travel through time. What makes her notable is that her power breaks one of the fundamental laws of time travel in the Marvel Universe: That one is unable to change their own universe's past, and that any changes will result in the creation of a new universe. Tempus's power allows her to travel through her ''own timeline'' at will, sometimes with catastrophic changes to the future she's unable to anticipate (such as a small change in the past wiping out the family she had in the future).* ''Comicbook/LokiAgentOfAsgard'' inverted the trope as the villain [[spoiler:(King!Loki)]] was doing the time travelling (they tried to cause their own creation earlier) and not only did this make the world a better place (no Angel/Asgardian war, made Odin actually admit that he loves his children etc.), but messed up the timeline so much that they'll never exist.* ''ComicBook/ArchieComicsSonicTheHedgehog'' did this for the "Mobius: 25 Years Later" storyline - King Sonic goes back in time to fix what was tearing Mobius apart, but accidentally creates a timeline where he accidentally pushes himself out of history and allows Shadow to be the world's savior. Shadow ends up being a cruel ruler, leading to Sonic, Tails, Knuckles and Knuckles' daughter Lara-Su to overthrow Shadow and set things right.* In the "Elegant Chaos" arc of ''ComicBook/TransformersMoreThanMeetsTheEye'', [[spoiler:Brainstorm]] travels back in time, with the hope of influencing Megatron's life so that he doesn't turn into the vengeful, murderous, power-hungry warlord who not only formed the Decepticons but started the civil war that killed millions. Ultimately he fails and by the end dawns the realisation that it is ''because'' he travelled back in time that the war began. NiceJobBreakingItHero.** Roberts is kind enough to show us the appalling potential consequences of a ''lack'' of the war too, though. Cybertron's corrupt government is not overthrown because the Decepticons never rose up against it and in time was hijacked by [[FantasticRacism Functionalists]], religious fundamentalists who enforce an increasingly strict social hierarchy with themselves firmly at the top. As time goes on they become powerful enough to bring into force 'obsolescence chips' which can insta-kill any Cybertronian not deemed useful enough - or who proves too rebellious. By the present day, Cybertron is a totalitarian police-state where constant surveillance, casual racism, and punitive mutilations are the norm.

[[/folder]]

[[folder:Fan Works]]* ''VideoGame/FinalFantasyVII'' fic ''FanFic/TheFifthAct'' has this when Cloud accidentally time travels to ''VideoGame/CrisisCore''. It starts with Cloud curing Genesis of his degeneration which results in him getting a new lease on life and not defecting. Which results in Sephiroth never going crazy because he still had his friends...[[spoiler: and results in Angeal defecting and betraying Cloud due to suffering degeneration alone and becaming desperate for a cure. Which results in Cloud falling to madness and getting possessed by Jenova.]]* Creator/HansVonHozel's ''Series/DoctorWho'' fic has a time travel related accident with a feather duster which causes the world's population to turn into dinosaurs... [[CrossesTheLineTwice who eat the Doctor]]... [[EpicFail and conquer the world]]...* In ''Fanfic/MementoVivere'', a VideoGame/FinalFantasyX fanfiction, the time-travelling protagonist, Rikku, asks herself this question repeatedly over the course of the story, as the actions she takes could potentially negate Yuna's future destruction of Sin. * The ''Literature/{{Worm}}'' fic ''FanFic/{{Security}}'' subverts this trope, as the [[Main/SelfInsertFic SI]] uses Contessa's power (Path to Victory) to ensure that any changes he makes to the timeline due to his mucking about with his future knowledge don't cause any major unintended side effects.* The ''Manga/CardCaptorSakura'' fic ''FanFic/ShadowOfTheDragon'' features such an example in chapter 8; Sakura uses the [[ResetButton Time Card]] to travel back in time by one day to save Tomoyo's mother from dying in a car crash courtesy of a drunk driver, but as a result, her classmate Reiko Ichimai is hit by said drunk driver instead. According to Cerberus/Kero and Yue, regardless of what Sakura tried to do, someone ''was'' going to die that day, and her interference just changed who died and when.* In ''[[https://www.fimfiction.net/story/302805/would-it-be-worth-it Would It Be Worth It]]'', Twilight, during the season 5 finale, attempts to [[SetRightWhatOnceWentWrong go back further in time and prevent Our Town from ever existing]] to stop Starlight. However, in the process, [[spoiler:she's confronted by a future version of her, who warns her that doing so would only make things worse due to this trope: ANY alteration to the past will have a ripple effect, not just negative ones like Starlight's. [[NothingIsScarier We don't see what the future she would've created was like]], but it's implies her Spike didn't make it back and either her or Starlight's counterparts in that timeline became the villain. Twilight decides to stop and restore the proper timeline.]]* ''FanFic/RosarioVampireBrightestDarkness Act III'': When Luna discovers from her [[CainAndAbel evil sister Falla]] that Rason is destined to die during the fight against Kiria, she promptly leaves to find a way to change his fate. Unfortunately, it's revealed in chapter 40 that Luna was supposed to be present in the original timeline during the fight against Kuyou, and save Astreal from death at Kuyou's hands; with Luna's departure, Kuyou torches Astreal with no effort. On top of it all, Falla, [[{{Jerkass}} heartless bitch]] that she is, knew that Astreal was doomed to die without Luna all along and deliberately neglected to inform Luna as such until it was too late.[[/folder]]

[[folder:Films -- Live-Action]]* The ''Franchise/BackToTheFuture'' trilogy:** The majority of the first ''Film/BackToTheFuture'' movie is Marty trying to reverse the effect of his having saved his father from being hit by a car.** Over the course of the trilogy, changing the past has nothing but positive effects for most of the characters. But ''not intentionally''. In fact, almost all of Marty's ''intended'' timeline changes end up nearly erasing him from existence. All the positive changes came from ''unintentional'' changes -- most notably his "Darth Vader from the planet Vulcan" schtick, intended to spook his teenage dad into asking for a date, instead gave him confidence to become a professional science-fiction author.* "Timewaves" are the result of the change in history in the very loose film adaptation of ''Film/ASoundOfThunder''.* ''Film/TheButterflyEffect'', named for the effect that names this trope. It's also notable for [[spoiler: the protagonist not only learning that messing with time can have disastrous consequences, but also realizing that he himself is the product of someone tinkering with fate. The world cannot be righted unless he does not exist]]. Only in the director's cut, not the original theatrical release ending.* This is played with in ''Film/DonnieDarko''; the setup is the same, and the plague of strange events that follow lead him to return in time [[spoiler:and allow himself to be in bed when an airplane engine crashes into his house, thus saving his girlfriend's life in a roundabout way. A subversion: in the original timeline [[http://www.cracked.com/article_19898_5-heroic-movie-deaths-that-didnE28099t-actually-help-anyone.html bad things happened ''without'' Donnie around to stop them.]]]] More than that, the DVD commentary says that Donnie's purpose was [[spoiler:to give the plane engine a reason for existing, preventing the collapse of the universe.]]* Inverted in ''Film/TheTimeMachine2002'', wherein Alexander Hartdegen's repeated attempts to go back in time to save his fiancée Emma inevitably go wrong. Later, the Uber-Morlock explains that the reason he cannot save Emma is that her death was his prime motivation for building the time machine.* In the film ''Film/{{Frequency}}'', a shortwave radio and the Northern Lights allow the main character to communicate with his father thirty years back in time. [[spoiler:Their conversations accidentally lead to the protagonist's mother (a nurse) saving the life of a serial killer who, in the original timeline, received a fatal overdose of medicine in the hospital. Since the murderer already had an obsession with nurses, and realizes she saved his life, this has worrisome consequences.]]* The movie ''Film/SlidingDoors'' had a non-time travel variation. The movie follows the events following the protagonist either missing the subway or getting on just in time, and then some...* The film ''Mr. Destiny'' starring Jim Belushi as Larry Burrows, an unhappy middle aged office employed loser. He blames the state of his life on the moment he struck out in a high school baseball game. A guardian angel like figure named Mike (played by Michael Caine) changes the past so that he hit the ball. Larry is now the president of the sporting goods company he worked and married to the owner's daughter. However, he soon learns that his alternate self's other decisions have a number of problems: his father is now divorced (on "his" advice, no less), he's having an affair with an AxCrazy worker, his best friend is now afraid of him, he's been involved in some shady schemes with the other executives who are now plotting to get rid of him after noting his "change of heart" and his wife from the original timeline is now married to someone else.* In the Franchise/StargateVerse film ''Film/StargateContinuum'', [[spoiler: Ba'al]] has gone back in time and [[spoiler:stopped the Stargate from reaching the United States in WWII, also killing Mitchell's great-grandfather, who was also transporting the Stargate to the US]]. This is made more interesting when the main characters, who know about the normal timeline, ask to be allowed to fix things, only to be told by General Landry that the people in this timeline don't ''want'' to be involved in big intergalactic wars. They like things just fine the way they are.* Perhaps the Aesop of ''Film/LolaRennt'' is that it's all just a crapshoot. Any given ripple of influence from a chance passing could be a ButterflyOfDoom -- or a miraculous windfall -- for Lola or anyone she brushes with. The opener alone establishes that fighting fate is just a game.* ''Film/FishStory'' is one big butterfly effect, tracing from the initial recording of a before-its-time and rapidly forgotten musical number to how that particular bit of music sets in motion a chain of events that saves the world.* ''Franchise/{{Terminator}}'':** Invoked in the series -- in that it is the machines' plan to alter their present by meddling with the past. Yet curiously averted in that they kill a whole bunch of people other than Sarah or John seemingly without affecting anything.** ''Film/TerminatorGenisys'' brings this even further even by estabilishing the "crushed butterfly" that creates an AlternateTimeline: [[spoiler:once John Connor undergoes an UnwillingRoboticisation in the future, the history up to that point is altered.]]* In ''Film/HotTubTimeMachine'', in which the protagonists are transported from 2010 to TheEighties in a hot tub, they are smart enough to avert this. They even reference the butterfly effect. They set out to do everything their '80s selves would've done in the same way they would've done it. [[spoiler:Then played straight in the end, when at the very last minute one of them decides to stay as his past self and re-live his life with everything he knows about the future. Then subverted in that this ends up being a really positive thing for everyone involved.]]* ''Film/Timecop2TheBerlinDecision'': The villain, who was one of the former students of the protagonist's father (a physics professor and time travel theorist), has a heated argument at a lecture in 2002 about whether time travel implies an obligation to [[SetRightWhatOnceWentWrong undo the tragedies of the past]]. His teacher warns him about the possibility that something worse may happen in their place.* Played with in ''Film/TimeChasers'', where a nerdy scientist invents a time machine, and then has to go back in time and prevent an earlier version of himself from giving it to a CorruptCorporateExecutive. The original versions of the scientist and his girlfriend end up dying while the "earlier" versions of them manage to keep the time machine from falling into evil hands.[[/folder]]

[[folder:Literature]]* The archetypal example -- from which the trope name descends -- would be Creator/RayBradbury's 1952 short story ''Literature/ASoundOfThunder''. There is a "Time Safari" where you can go back in time and hunt any animal. It is a DefiedTrope here because they specifically look for animals who are going to die and go back in time to just before they do, and have an anti-gravity path to shoot the animal from. [[spoiler: Naturally, something goes wrong: the cocky Eckels is scared as heck when he sees his T-Rex, and runs off the path. When they go back to the present, the Hitler-esque Deutscher wins the Presidential election instead of Keith. There is also a different alphabet. And all because, you guessed it, Eckels accidentally stepped on and killed a butterfly.]] This is a Trope Namer; the other TropeNamers drew inspiration from this one.* Similarly, the science-fiction story "Aristotle and the Gun" by Creator/LSpragueDeCamp has an arrogant time traveler trying to change history, and achieving the exact opposite of what he intends.* Both the novel and the film ''Literature/{{Millennium}}'' conclude with a runway "timequake" obliterating the future, because of an accidental change made to the timeline in the present.* An ''Literature/{{Animorphs}}'' Super Special dealt with a villain changing time. Some things were better, some things were worse; [[HitlersTimeTravelExemptionAct World War II]], of course, was one of the affected areas. Much of the conflict of the book is over whether to restore the world or keep it the new way, and what justifies preserving bad pieces of history.** There was also another storyline where we find out what would have happened if the main characters hadn't run into the alien who gave them superpowers and warned them about an alien invasion.** In fact, Cassie's history teacher Ms. Paloma makes a reference to the butterfly thing in Book 7, ''The Stranger''. See [[http://en.wikipedia.org/wiki/List_of_minor_humans_(Animorphs)#Teachers here]].* ''Literature/TheGreenFuturesOfTycho'' by Creator/WilliamSleator involves a time traveler teenager making repeated trips into the future. Each time he discovers a bad future, and tries to fix it in the present or past. Each time, his actions only make it worse. He eventually realizes the reason ([[spoiler: In all futures, he has the time machine and he's using it to control events]]), but not before he gets his time-traveling EvilOverlord future self chasing him to stop himself from messing up the past (present for the teenager) that lead to his present (future).* Creator/IsaacAsimov's novel ''Literature/TheEndOfEternity''. Only in this case, the constant changing of the potential timelines by a secret trans-temporal time agency resulted not in unpredictable chaos but in a static history, because the time agency tried to erase, with the best intentions, every invention, trend or development that they regarded a danger to Mankind and human life in general... erasing wars, but also deliberately killing all attempts at space exploration throughout the various milennia. In the end, only the destruction of the time agency itself allowed the restoration of Mankind's original timeline: a life full of risks in search of the Unknown, but also with the potential to colonize the galaxy and survive into the distant future after the Earth's sun had gone nova.* This was subverted in Creator/TerryPratchett's ''Discworld/TheLastContinent''. When the faculty of the Unseen University find themselves trapped centuries or even millennia before they were born, Ponder Stibbons invokes the ever-popular "kill your own grandfather" example of why you shouldn't muck around with the past. Arch-chancellor Ridcully dismisses Ponder's concerns with a logical "whatever happens stays happened" attitude. He points out that having killed one's own grandfather and ceased to exist, no-one would exist to step on the ant, meaning your grandfather was never killed. This creates a circular paradox; doing something makes you unable to do it. He also observes that he is unlikely to kill his own grandfather, as he "rather liked the chap." Therefore, since they are in the past, they were clearly there once already (i.e. now), and therefore any ants that are stepped on, are vitally important in their capacity for being stepped on. The Bursar later attempts to take this to heart by jumping around on ants in between walking into trees.** This subversion of the Butterfly of Doom theory is itself a [[StableTimeLoop well-respected alternate theory]] of how time travel might work; in a real sense Ridcully is simply the Discworld inventor of an idea that many writers of time travel stories already accept in our world.** Directly parodied with the Quantum Weather Butterfly, flocks of which played a big part in Discworld/InterestingTimes. The Quantum Weather Butterfly uses its ability to affect localized weather phenomenon as a form of self-defense, and possibly a way of attracting mates. "Hey baby, look at this thunderstorm!" (And of course, Pratchett [[ShownTheirWork Shows His Work]] by pointing out that the fractal nature of the edge of the Quantum Weather Butterfly's wing makes it quite finite in area, but nearly infinite in perimeter, which is one of the seeming paradoxes of fractal surfaces in real life.)*** Alas, no. While probably a deliberate 'error' attributed to Discworld logicians, the statement in the book is actually less mathematically sound:

---> And therefore, if their edges are infinitely long, the wings must logically be infinitely big.

---> They may look about the right size for a butterfly's wings, but that's only because human beings have always preferred common sense to logic.

** [[FanNickname Pterry]] plays with theories of time travel/the Butterfly Effect a lot. A good example is ''Discworld/NightWatch'', where despite the fact that when John Keel, an important figure in the storyline, is killed because Vimes turns up 30 years in the past, Vimes ends up taking his place more-or-less seamlessly. Lu-Tze, the history monk, muses on the nature of time:--->'''Lu-Tze:''' We're learning a lot, though! For a perfectly logical chain of reasons Vimes ended up back in time even ''looking'' rather like Keel! Eyepatch ''and'' scar! Is that Narrative Causality, or Historical Imperative, or Just Plain Weird? Are we back to the old theory of the self-correcting history? Is there no such thing as an accident, as the abbot says? I'd love to find out!:::and later...-->'''Vimes:''' I mean, doesn't it change history if you tread on an ant?\\'''Qu:''' For the ant, certainly.\\'''Lu-Tze:''' I told you, Mister Vimes. History finds a way. It's like a shipwreck. You're swimming to the shore. The waves will break whatever you do. Is it not written, "The big sea does not care which way the little fishes swim"?** ''Witches Abroad'' laments that scientists aren't getting in with 'proper science'--->Like finding that bloody butterfly whose flapping wings cause all these storms we've been having lately and getting it to stop.* Creator/MadeleineLEngle's ''Literature/ASwiftlyTiltingPlanet'': Mad Dog Branzillo will succeed in nuking the earth unless [[spoiler: Charles Wallace goes back in time and changes the Might-Have-Beens in humanity's history. Thus, Branzillo's very distant ancestors never waged a fratricidal war; his blue-eyed ancestor Zylle was never hanged as a witch; the descendants of the two brothers married, and "Mad Dog" Branzillo was instead born El Zarco, "the Blue-Eyed".]]* In the third book of ''Literature/ThePendragonAdventure'', ''The Never War'', the characters at first think that to make the turning point go correctly, they must stop the destruction of the Hindenburg. However, they ask the Traveler from Third Earth (the far future) to analyze what would happen if they did it. It turns out that the world would be destroyed if they went through with it. After a rather huge misunderstanding because one character didn't get that last bit of info, they manage to let time go on its proper course.** And then, in the later books, Mark brings incredibly advanced technology into the past, jump-starting the computer industry and advancing technology's development. Of course, also thanks to Mark, we also get the future dystopia seen in ''Raven Rise'' because of a stupid decision he made in 1939.* In Marge Piercy's ''Woman on the Edge of Time'', it's implied that the apparently futile actions of a single patient in a mental institution will affect whether the future holds a sustainable, egalitarian utopia or a polluted colony of virtual prisoners and sex-slaves.* Alfred Bester's ''The Men Who Murdered Mohammed'' plays around with this. A scientist attempts to erase his wife's existence after he finds her cheating on him. He whips up a time machine, and goes back in time to kill her grandfather. The catch? It doesn't work. So, he works bigger, rampaging through time, killing more and more famous people with absolutely no effect on the present until, finally, [[spoiler: he meets a fellow time traveler who explains that the past he's killing is his own, [[IronicHell and he's unhinged himself from reality because of his actions.]]]]* The ''Literature/ChildrenOfTheLamp'' series has a non time traveling example. Philipa (a djinni) grants an innocent wish of removing all foie gras from New York city. But it takes a horrible turn in that through an unusual series of events [[spoiler: it destroys her mother's body in a volcanic eruption. Fortunately her mother is a djinni thus she was able to survive and a friend had earlier been in an accident that had left that friend brain dead.]]* Invoked in a small way, along with FailureIsTheOnlyOption, as part of a brutally satirical short story in Creator/StanislawLem's ''Literature/MemoirsOfASpaceTraveller: The Further Reminiscences of Ijon Tichy''. Attempts to correct problems in history and create a better world fail spectacularly due to a combination of mishap, incompetence, and malice, resulting in a thoroughly fouled-up world —- the one we currently live in.* Hilariously lampshaded/satirized in Creator/WilliamTenn's short story "Brooklyn Project", which opens with the acting secretary to the executive assistant on press relations explaining to a group of journalists that the project to send a probe four billion years into Earth's past -- and then two billion, and then one billion and so forth -- is perfectly safe, that nothing that happens in the past can change the present. In brief vignettes we see the probe condensing moisture on its outer surface, the probe destroying microorganisms with its weight, the probe crushing tiny trilobites... and the story ends with "the thing that had been the acting secretary to the executive assistant on press relations" spreading his tentacles and explaining that ''as they can all see'', nothing has changed.* Directly referenced in the fist chapter of the first ''WesternAnimation/CodeLyoko'' novel, "The Butterfly at the Bottom of the Sea". The butterfly is the minuscule disturbance of a cable deep beneath the Sea of Japan, and the end result is [[spoiler:XANA's revival and Aelita's memory loss.]]* {{Invoked}} in ''Literature/ScorpionShards'', where Dillon intentionally searches for the proverbial butterflies he can kill to cause huge catastrophes.* In ''Literature/TheWiseMansFear'' the Cthaeh, an entity unable to leave a single tree, has perfect knowledge of all possible futures, and whenever it speaks to someone, it manipulates them into causing the greatest possible harm with just a few words. Policy on handling those who speak to it is to shoot them dead from half a mile away, leave the body to decompose, and if a crow descends to eat the body, shoot the crow. And perhaps as a reference to the trope name, it spends its time setting up whatever little details it can so as to kill very specific butterflies that've come anywhere nearby.* The historians in Creator/ConnieWillis's time-travel novels are afraid of this happening, because although for many years they've believed that the laws of time-travel physics don't allow anyone to travel if their presence will change history, this isn't borne out by their own experiences -- while they can't visit "divergence points" (for example, the battle of Waterloo, or anywhere near Hitler) they ''can'' alter minor events, and then have no way of knowing whether this has had a significant effect. The plot of ''To Say Nothing of the Dog'' balances on whether two individuals will marry each other instead of the people that they're required to marry so that their descendants exist in the future in order to play historical roles. In ''Blackout'' it's posited that a novice time-traveler bumping into a woman and making her drop her handbag may cause the Allies to lose WWII. [[spoiler: However, in both novels, the continuum appears either to self-correct, or to have "required" the presence of the time-travelers -- in other words, the things they do have always happened and don't change the overall outcome of events.]]* In the short story "You're Another" a hapless man finds that all of his troubles are caused by people from the future who alter the past, over and over again, and then film it as entertainment. When asked if changing the past doesn't change their time in the future, they explain that it doesn't, saying "What happens to a dog when you cut off its mother's tail?" He is not happy when he finds out his part in all this, and why he's constantly falling into holes, having paint drop on him and being cheated on by his girlfriend. Their explanation: [[spoiler: "comic relief"]].* Played with in ''Literature/ElevenTwentyTwoSixtyThree''. While changing the past does have major negative effects, some of them are the result of the timestream shattering. [[spoiler: For example, saving Kennedy leads to a massive Los Angeles earthquake ''the same week'', which could not possibly have been a direct result.]]* Averted with Creator/LarryNiven's "Hanville Svetz" series. The time traveling agents of the Institute For Temporal Research do not realize that time travel is nothing more than a fantasy, so when they go backwards in time (forward time travel being impossible because the future does not exist yet), they always end up in some fantasy world. In "Flight of the Horse", for example, Hanville Svetz is sent back in time to retrieve a horse (long extinct in his time) for the government-run zoo . . . and brings back a unicorn.* In "Because a Little Bug Went Ka-Choo!", by Rosetta Stone (aka Dr. Seuss), a bug sneezes, setting off a series of larger and larger consequences, in the end nearly sending a whole town into chaos.* ''Literature/TimeRiders'' is centred around stopping people from a seemingly hopeless future from changing the past. Only the odd book has no massive effect on the future due to something being changed in the past as its main plot.** In ''[=TimeRiders=]'', Kramer tries to lead Hitler to victory and grab some glory for himself too. [[spoiler:Kramer eventually goes insane and starts a nuclear war, leaving nothing but savage mutants on the planet]].** In ''Day of the Predator'', an assassin [[spoiler:(later proven to be a HitmanWithAHeart when he doesn't kill Chan)]] is sent to kill young [[AssassinOutclassin Edward Chan]], one of the biggest contributors to the invention of time travel. Thankfully, we see very little of the BadFuture that would occur.** In ''Doomsday Code'', Liam finds himself in the middle of a [[spoiler:History-changing battle. Time is in a state of flux until the battle is over]].** In ''Eternal War'', the Eternal War in question is the result of UsefulNotes/AbrahamLincoln not being around to win the American civil war.** In ''Gates of Rome'', the Project Exodus team tries to overthrow the Roman Empire. [[spoiler:Instead, everyone but Rashim is killed and Emperor Caligula uses the support units the team had as his personal bodyguards, leaving him to rule for far too long]].** In ''City of Shadows'', the team run into Jack the Ripper [[spoiler:and figure out that they have to let him get away with his murders; he is actually an aristocrat, and the discovery of that would leave London in ruins]].[[/folder]]

[[folder:Live-Action TV]]* ''Series/{{Angel}}''. In "[[ItsAWonderfulPlot Birthday]]" the demon Skip shows Cordelia (with the help of MondayNightFootball replay and onscreen graphics) how her life could have been different if she'd just moved in one direction as opposed to the other during a party in the series premiere and met a Hollywood talent agent instead of the series protagonist, becoming the famous star of a comedy television series instead of a FaintingSeer whose visions are killing her. [[spoiler:The downside being, ''Angel'' is now the FaintingSeer, effectively an insane, depressed wreck from [[GoMadFromTheIsolation his loneliness]] and the visions. Horrified by the state of her best friend/LoveInterest, Cordelia demands that Skip take her back to her proper timeline.]]* ''Series/{{Blackadder}} Back and Forth'' is a brilliant example of this trope. In the story, Baldrick (accidentally, Blackadder meaning it as a scam to win a bet with his guests) invents a working time machine. They're sent on a dare to use it and to bring back a catalogue of different items including a centurion's helmet and the Duke of Wellington's boots. After Blackadder succeeds, it emerges that he has changed the course of history as a result: After finally arriving at the battle of Waterloo, he squashes the Duke of Wellington with his time machine just before the battle begins, steals his famous boots and causes the French to win the fight. As a result, Blackadder returns to an alternate-reality Britain which has been ruled by the French for 200 years -- as a result of his tampering -- following Napoleon Bonaparte's victory at Waterloo, and just in time for garlic pudding. He becomes especially disconcerted when he sees Archdeacon Darling wearing a tutu and exclaims "We've got to save Britain!" before going back in time to try and rectify everything. He also has a run-in with William Shakespeare, earlier on in the story, whom he attacks for the interminable suffering of school pupils that would happen for the next 400 years as a result of having to study his plays at length, leaving William completely discouraged as a playwright but dropping his ballpoint pen in the process. Later on, in the alternate reality, William Shakespeare is revealed to have been known only for "inventing the ballpoint pen." Eventually he learns to manipulate history consciously so he becomes the king in the present and marry Maid Marian.* The ''Series/{{Community}}'' episode "Remedial Chaos Theory" is all about this. It's decided that a roll of the dice will dictate who has to leave and pick up a pizza, so the one rolling the dice will be creating six different universes, all based around what the characters would or (or in some cases, wouldn't) be doing in the two or three minutes that the pizza is getting picked up. All outcomes except for one involve the group somehow creating a conflict in these couple minutes. In the real (best) outcome, [[spoiler:Abed stops the dice from falling, Jeff goes to get the pizza, and the group gets along fine while he's gone.]] In the "Dark" outcome [[spoiler:where Troy leaves to pick up the pizza, Pierce dies, Annie goes insane and Shirley becomes an alcoholic because of Pierce's death, Jeff loses an arm, and Troy loses his larynx.]] Abed acknowledges that it's the darkest timeline, and makes everyone felt goatees so they can all be "evil" versions of themselves.* Invoked in the 2014 ''Series/{{Cosmos}}'' series. UsefulNotes/NeilDeGrasseTyson uses three butterflies in a cloud of white moths to represent the concentration of carbon dioxide in the atmosphere because the variations needed to radically change the climate are so mathematically small--no butterflies, and the Earth freezes, three more butterflies and it heats up. He also mentions the "butterfly effect" of chaos theory (tiny changes in starting conditions lead to entirely different results) when explaining the difference between weather (chaotic) and climate (not).* Spoofed in ''Series/Danger5''. Our heroes travel back in time to UsefulNotes/WorldWarII and despite [[OnlySaneMan Pierre]] frantically trying to convince them of this trope proceed to kill Nazis with abandon, party with their younger selves, and SetRightWhatOnceWentWrong. This results in a BadFuture -- not because of anything they did, but [[HitlersTimeTravelExemptionAct because they were stuffing about instead of concentrating on their original mission: KILL HITLER!]]* ''Series/DoctorWho'':** The Doctor has mellowed a bit when it comes to messing around with history. The First Doctor, in [[Recap/DoctorWhoS1E1AnUnearthlyChild "An Unearthly Child"]] is so paranoid about the possible ramifications of this trope that he is convinced that the mere ''idea'' that a device such as the TARDIS exists could irreparably change the course of human history.** In the episode [[Recap/DoctorWhoS27E8FathersDay "Father's Day"]], Rose goes back in time to visit her father before his death but ends up saving him from his fatal accident. The resulting tear in the fabric of reality lets through a host of aliens who feed off time energy and kill a lot of people.** In [[Recap/DoctorWhoS29E2TheShakespeareCode "The Shakespeare Code"]], the Doctor lampshades this to put Martha at ease in her first time time-travelling.--->'''Martha:''' It's like in those films. You step on a butterfly, you change the future of the human race.\\'''The Doctor:''' Then, don't step on any butterflies. What have the butterflies ever done to you?** [[Recap/DoctorWhoS30E2TheFiresOfPompeii "The Fires of Pompeii"]] both plays this straight and subverts it. Donna asks the Doctor why he can't warn the city of the impending volcanic eruption, only for him to say that it's a fixed point in time that must not be tampered with. At the end, as the volcano is erupting, Donna pleads with the Doctor to help, so he rescues one family (the one they've gotten to know throughout the episode) and puts them outside of the city with what appears to be no consequences.** While the show is mostly immune to this trope, with characters messing through time willy-nilly, it is used occasionally. The episode [[Recap/DoctorWhoS30E11TurnLeft "Turn Left"]] is probably the most striking example, with an ItsAWonderfulPlot twist.** In [[Recap/DoctorWhoS31E12ThePandoricaOpens "The Pandorica Opens"]], it happens in a big way when the TARDIS explodes and rips up time, so much so that every star in the universe is never born and he only reason life exist on Earth is that the TARDIS is exploding at all points in time. To fix it, the Doctor has to take the Pandorica to the TARDIS and have it explode, sending all the atoms of the old universe everywhere in every point of time, effectively Big Bang 2, but he will be stuck on the other side of rip. He gets better, though.** In [[Recap/DoctorWhoS32E13TheWeddingOfRiverSong "The Wedding of River Song"]], River Song tries to subvert reality by [[spoiler:not killing the Doctor]]. The result of this is that all of time and space coexist in the same eternal instant, with anything unable to happen until the proper events of the timeline are carried through.** Mocked in [[Recap/DoctorWhoS36E3ThinIce "Thin Ice"]], where new companion Bill worries about doing this. The Doctor assures her she must be careful, like their other poor companion who just stepped on a butterfly and erased himself from existence! [[BlatantLies That's why she can't remember him]]. The lesson being little things don't have that much of an impact.* Comes up in several episodes of ''Series/{{Farscape}}'':** In season three's "...Different Destinations," the crew find themselves sent back in time by a freaking out Stark while visiting a monastery saved from destruction by Peacekeepers. In addition to the BrokenPedestal for Aeryn when she learns the great hero of the battle turned out to merely be the company cook, the crew has to deal with an escalating series of alterations to the timeline with ''catastrophic'' implications for the future (including, at one point, the planet ''ceasing to exist'') as they attempt to keep events on their historical course (Harvey having told John of the theory of time's elasticity, and that events steered near-enough to course will lead to time self-repairing). Eventually they set things more or less right and return home, [[spoiler: but the women and children who originally survived instead ended up being slaughtered in the "fixed" timeline, and the crew is unable to go back again to save them]].** The danger of this is further highlighted by the Einstein in season four's "Terra Firma," warning that using a wormhole to travel to a point in time in one's universe ''before'' the time one departs can have disastrous consequences. The following episode, "Kansas", follows up on this when John accidentally travels to his own past and his arrival somehow changes time so his father is fated to fly the doomed ''Challenger'' mission. The crew manages to avoid making any major ripples as they trigger a series of events which Crichton recalls led to his father withdrawing from the mission (specifically shacking up as a teenager with Karen Shaw in the back of his dad's four-by[[note]]actually Chiana in the back of John's truck, with Noranti using a bit of mind control to alter the exact memory[[/note]] at an abandoned house, which caught fire and nearly killed him, only for his dad to rescue him and beg off the mission until he recovered). By the end, the episode actually wavers on how much their actions are avoiding the Butterfly of Doom, or are actually the result of a PredestinationParadox.* ''Series/{{Fringe}}'': In a roundabout way, the show reveals in bits and pieces that the entire plot of the series and the fate of multiple universes all pivoted on a single inadvertent action by a time traveler: [[spoiler:an Observer's presence distracting the red universe's Walter Bishop from discovering a cure for his son Peter's illness]]. This miniscule action caused [[spoiler:Walter's blue universe counterpart to bridge their two universes to save Peter, and then kidnap him to be a ReplacementGoldfish for his own Peter]]. This dimensional mess destabilized the physical laws of both universes and jeopardized the timeline that would spawn the time-travelers in the first place, forcing them to take a direct role in correcting the original mistake.* ''Series/{{Heroes}}'':** A big part of the show, with time travel (mainly by Hiro Nakamura, and later [[spoiler:Peter Petrelli]]) and precognition being used to fix, worsen, and then repair the future many times. Featured most prominently in the episode, "The Butterfly Effect", where Future Peter screws up the past so badly, that he leaves things for Present Peter to fix since he had "stepped on too many butterflies."--> '''Angela Petrelli:''' [[DiscussedTrope It's called the Butterfly Effect. You step on a butterfly today, three years from now a million people are wiped out.]]** Possibly subverted, or at least morphed into YouCantFightFate, during Volume 4 where [[spoiler: all of the things that happened in the "averted" future are happening anyway (Sylar can heal and shapeshift, Nathan has turned on the mutants, Sylar-As-Nathan is gunning for president, etc.]].** Heavily subverted with Charlie. Through Hiro's intervention, she is saved from her brain tumor and Sylar's murder-spree. But she is kidnapped and stranded in the 1940's in order to manipulate Hiro. Before she went, she was an insatiable reader and had the super-power of 100% perfect memory - someone with enormous potential to alter history for good or evil. Yet she does...nothing, instead choosing to work a factory job and settle down.* The ''Franchise/KamenRider'' [[MilestoneCelebration 40th anniversary movie]] ''Let's Go Kamen Rider'' is all about this. [[Series/KamenRiderOOO OOO]] and [[Series/KamenRiderDenO Den-O]] chase a monster back to the era of the original Series/KamenRider and accidentally leave behind an [[TransformationTrinket O Medal]]. When they return to 2011, that single Medal has allowed villain organization Shocker to TakeOverTheWorld and put four decades' worth of Kamen Riders on the ropes.* Used in the UK series ''Series/{{Misfits}}'', where Curtis uses his time-travelling ability to go back to the night he and his girlfriend Sam were arrested for drug possession. His initial attempts to change things only make things worse (such as Sam ending up stabbed by the dealer), but he eventually manages to change things enough that neither of them is killed or arrested and "jumps" back to the present, where it looks initially like an inversion; he's back to being an Olympic athlete and Sam is alive. Then he realises that without him there to save them, almost the entire main cast were murdered back in the first episode.* ''Series/MrYoung'': "Mr. First Impression". Adam going back in time to make a better first impression on Echo leads firstly to his getting fired, then to Echo dumping him for a criminal kingpin, and finally to elephants beating humans in a war for control of the Earth.* ''Series/MysteryScienceTheater3000'': The host segments of the ''Film/TimeChasers'' episode play around with this trope, with Crow going back in time to prevent Mike from getting shot into space. Unfortunately, Mike dies in this alternate fate-line and his {{Jerkass}} older brother Eddie ends up on the SOL instead. Crow goes back in time again to tell the earlier version of himself ''not'' to warn Mike, and, as a result, the earlier version of himself gets stuck in the past where he will presumably remain, as an employee of the cheese factory where Young Mike worked.** In another episode, featuring ''[[Recap/MysteryScienceTheater3000S11E03TheTimeTravelers The Time Travelers]]'', Gypsy quizes Tom on what to do if he found a portal to the 1920s. When he suggests that he'd go back in time and become the greatest gangster ever, Gypsy proclaims he just caused the future to become a nuclear wasteland. When Tom calls her on that, Gypsy says that it ''always'' happens.* A continuing theme of the CutShort series ''Series/OdysseyFive''. Five astronauts who survived the destruction of Earth are sent back in time five years to try and avert the xenocide. Although they agree not to try and change their own personal lives none of them can resist trying to tinker with events, with varying results.* Subverted in an episode of ''Series/{{Scrubs}}'' appropriately entitled "My Butterfly", where a butterfly affects the events of the day, ending in the death of a patient. When the butterfly changes where it lands, the episode features an alternate future, but [[spoiler:the patient that J.D., Dr. Cox, and Turk are involved with still dies on the table]].* There is a sort of this in ''Series/SevenDays''. It's stated that simply backstepping (Going back in time one week) already changes the timeline because the Sphere materializes and changes air currents, causing airplanes to land a bit sooner/later and the like. Of course, it was never explained further than that.* The main character of the Korean crime drama ''Series/{{Signal}}'' shows fear of this after some disastrous results of meddling in the past involving two cold cases.* In ''Series/{{Smallville}}'', Clark goes back in time to save [[spoiler:Lana's]] life. However, in preventing the accident, [[spoiler:his dad]], no longer having a reason to stay and console Clark, goes straight to his meeting with [[spoiler:Lionel Luthor]]. The scuffle that ensues causes him to have a heart attack, ultimately killing him.* Several alternate universe/timeline episodes of ''Series/StargateSG1'' feature worlds where it seems like only one small thing has changed, but often, that leads to something even more horrible happening. A good example is "2010", where contact with one group of aliens leads to [[spoiler:the slow but inevitable destruction of Earth's human population]].* ''Series/StarTrekVoyager'': Another fine example of how one man's repeated attempts at changing the past to find the "perfect" timeline he accidently erased leading to ever more disastrous consequences is the two-parter episode "[[Recap/StarTrekVoyagerS4E8YearOfHell Year of Hell]]" from the 4th season. Things are spiraling out of control, precisely because the timeship is based on the idea of ''Laplace's Demon'' which is contradicted by both Quantum Mechanics and Chaos Theory. He keeps erasing ''entire species'' from existence to restore his species to their former glory, only for unanticipated consequences (one species introduced antibodies that saved his from being decimated by a plague, another prevented some other species from conquering them, etc.) to leave his species still weak or actually worse off. In the end [[spoiler:the original timeline can only be restored by destruction of the timeship (which had existed "outside time" while aboard centuries of subjective time passed), which Captain Janeway brings about by ramming it with the ''Voyager'', destroying both ships in the process and "resetting" the timeline back one year.]] * Both mocked and utilized in ''Series/{{Star Trek|The Next Generation}}'' by Q in "Tapestry". While changing the past would certainly alter one man's future, it's incredibly self-centered to think that changing one person would change ''everything''.* In what is widely considered to be the best episode of ''Series/{{Star Trek|The Original Series}}'' (TOS), "The City on the Edge of Forever", the world falls to Nazi Germany and Starfleet never forms because one woman didn't die when she was supposed to.\\\\The story -- originally written by Harlan Ellison -- had been radically revised, by the time the episode was shot. So much that Ellison [[http://en.memory-alpha.org/wiki/The_City_on_the_Edge_of_Forever_(episode)#Story asked to be cited under a pseudonym]]. It's unsure whether -- at least, in part -- his displeasure with the final result had anything to do with the revised version's [[http://www.depauw.edu/sfs/backissues/62/franklin62art.htm subtext that opponents of the Vietnam War were comparable to appeasers of Hitler]].* ''Series/{{Supernatural}}'':** In "[[Recap/SupernaturalS02E20WhatIsAndWhatShouldNeverBe What Is And What Should Never Be]]", Dean is tricked into believing a Djin has taken him to an AlternateUniverse where his mom never died, and none of his family members became Hunters. Everyone's living happily, but as a consequence, his relationship with Sam is estranged because of their lack of time together, and all the people he saved as a Hunter died in their "accidents" without the brothers there to prevent them. Luckily, it was AllJustADream.** In "[[Recap/SupernaturalS04E03InTheBeginning In the Beginning]]", Dean is ''actually'' taken back into time by Castiel, who warns him that any attempt to save his mother will inevitably result in the death of the innocents he has saved. Subverted in that no matter what Dean did, things [[StableTimeLoop ended up going exactly the same]] way anyway.** In "[[Recap/SupernaturalS06E11AppointmentInSamarra Appointment in Samarra]]", a non-time travel related version happens when Dean [[GodJob becomes Death for a day]] and fails to reap a twelve-year-old-girl, the butterfly ensures that things go badly for everyone near her. For example, a nurse gets off early because her help wasn't needed and dies in a car crash. His husband sees her die and attempts suicide by car accident. Presumably, this kind of thing would continue forever.* Happens many times in ''Series/{{Timeless}}'', most notably in the first episode. After returning from the ''Hindenburg'' explosion in 1937 and changing history so fewer people are killed, Lucy finds out A) her mother, who was dying of lung cancer, is now perfectly fine, B) her younger sister, Amy, has been erased from existence, and C) she's engaged to a man she has never met before.* Hysterically parodied in a ''Series/TheWhitestKidsUKnow'' sketch. Every time Trevor and Sam try to change history, random things happen (because that's how physics works). They go back in time and kill Hitler; JFK turns into a panda bear. They stop two Godzilla-esque monsters from attacking each other and cause the Vietnam War. After preventing 9/11, one of the character's sister starts to disappear from a picture (a parody of ''Back to the Future''). In response, they scream "We have go back and save 9/11!" Seems the maker of the show didn't know anyone close to the attack.* ''Series/LegendsOfTomorrow'': The existence of time traveling superheroes means that the Legends can never make the timeline ''exactly'' the way it originally was -- it's always a case of CloseEnoughTimeline. That being said, there are certain moments/events that they can '''never''' time travel to for fear of risking this, since they are so pivotal to shaping history, such as ''anything'' having to do with Jesus, including his crucifixion and eventual death.[[/folder]]

[[folder:Music]]* Music/{{Vocaloid}}:** The butterfly-as-misfortune motif is used in the song "Butterfly on Your Right Shoulder".** In another Vocaloid song "ANTI THE∞[=HOLiC=]", black butterflies are used and seen throughout the song in many ways. The song is about the ignorance of people, though, and how [[CrapsackWorld poor a world]] [[MyGodWhatHaveIDone they can create]] [[HumansAreMorons with their own stupidity]].* Touch by Music/DeltaGoodrem refers to this very thing: --> I'm like a butterfly that moves its wings/There’s a storm happening somewhere* Referenced in Music/TheDivineComedy's track 'The Certainty of Chance':-->A butterfly flies through the forest rain,\\And turns the wind into a hurricane.[[/folder]]

[[folder:Radio]]* Creator/RayBradbury's radio drama version of ''Literature/ASoundOfThunder'' virtually has the same plot as the short story, butterfly included.* In AudioPlay/BigFinishDoctorWho, the Seventh Doctor gently tells Ace that it's "just a story we tell the butterflies", and that she should stop looking for one single moment in her life that will magically change everything. [[/folder]]

[[folder:Theater]]* ''Theatre/HarryPotterAndTheCursedChild''; After Albus and Scorpio use a Time Turner to [[spoiler: save Cedric's life by making him lose the first task of the Triwizard Tournament, he feels so humiliated that he joins the Death Eaters and kills Neville. As a consequence of this, Nagini never died, and Harry could never kill Voldemort, leading to a BadFuture where Voldemort ruled Britain]].[[/folder]]

[[folder:Tabletop Games]]* Averted in ''TabletopGame/FengShui'', where the universe actively ''resists'' attempts to change it. To illustrate it, the sourcebook gives the classic example of a man going back in time to kill his own grandfather. If Johnny Fong goes back in time and kills his grandfather, he returns to the present to find that his name is Johnny ''Wong'' now, but nothing else has changed. In ''TabletopGame/FengShui'', world history bows to the whims of the people in control of the world's feng shui sites, and anything done by insignificant time travelers just gets corrected.* One particular incident which was a footnote in ''TabletopGame/Warhammer40000'', Ork warlord Grizgutz lead his Waaagh! off to war the course of it brings him back home. Because [=FTL=] travel for most relies on going into [[HyperspaceIsAScaryPlace the Warp]], which has at best an orthogonal relationship to physics in realspace, he arrives home before he left to go to war. He then did what he felt was reasonable (for an Ork), he decided to kill his doppleganger to have a spare of his favorite gun. The resulting confusion made the Waaagh! stop in its tracks.* ''{{TabletopGame/Continuum}}'' averts this in a weird way. Time travelers come in two factions; Narcissists who want to use time travel to change history, and the Continuum which wants to keep things just as they are. The war between the two has a known ending; the Continuum wins. The Continuum must win, because if the Narcissists keep changing the past, existence vanishes in a PuffOfLogic. All existence. Thus, for the good of everyone ever born, there are no butterlies of doom. Not "the Continuum must stop them or existence will blink out." Rather, the butterflies at no point in the time stream happen, and this is known because existence still exists. That doesn't mean Narcissists won't try to change things (they believe existence can change) or that things happened the way you think they did.** If a Narcissist has a plan to insert a butterfly of doom, it fails. Of course, since you might not know what that plan is, you don't know exactly how history unfolded. For example, if a Narcissist tries to go back in time to stop Lincoln's assassination, it's entirely possible the narcissist killed John Wilkes Boothe - and a member of the Continuum replaced him. *** The Continuum operates by BlueAndOrangeMorality; since everyone, everywhere, at all times winks out if the timeline is damaged, ensuring even the most horrible events in history play out as recorded is paramount. Put another way, the Continuum would defend Pol Pot because letting Pol Pot be stopped - contradictory to the historical record - causes ''all existence'' to stop, ending ''countless'' lives. [[/folder]]

[[folder:Video Games]]* ''VideoGame/PrinceOfPersiaWarriorWithin'' actually uses this trope, but with a twist -- instead of unexpected consequences, there is an [[ClockRoaches actual guardian of time]] that hunts the Prince in order to restore time to its original flow.** Played straight in ''VideoGame/PrinceOfPersiaTheTwoThrones'' where the events of ''Warrior Within'' have undone the events of ''VideoGame/PrinceOfPersiaTheSandsOfTime'' [[spoiler:meaning the Vizier from ''Sands of Time'' is still alive and still searching for the eponymous sands, sacking Babylon in the process.]]* ''VisualNovel/TimeHollow''. The player makes small changes to the past and watches the subsequent results.** This is also the plot for the [=PS2=] game ''VideoGame/ShadowOfMemories'' which was written by the same maker of Time Hollow. Dude loves his time travel.* The basis for the ''VideoGame/CommandAndConquerRedAlertSeries''. The whole thing started when Einstein went back in time to kill Hitler, [[HitlersTimeTravelExemptionAct resulting in WWII taking place between the Soviets and the Western Allies]].** And in ''VideoGame/CommandAndConquerRedAlert3'', the Soviets go back in time to erase Einstein in order to save the Soviet Union, weakening both the Aliies and the Soviets(no nukes) and creating the Empire of The Rising Sun, resulting in a three-way world war.* ''VideoGame/BlazBlue''. Six words: [[ArcWords The Wheel of Fate is Turning]].** [[ScrewDestiny Rebel 1!]]*** Action!* ''VideoGame/{{Achron}}'' allows for rather odd situations involving chronoporters (time-teleporters) and battles. For example, by sending units back in time to fight alongside themselves, if the original units are damaged in the ensuing battle, the future versions will be also damaged when the next timewave comes by. Eventually, this can resolve into a much weaker army than was originally used. Also, these sorts of time-manipulation tricks can allow for armies to go back to attack economic or production structures to disrupt opponents. For example, killing ''that one marine'' who built all the resource processors that made the construction of the army that's harassing you in the future even possible. So, by killing one marine, you defeated an entire army. [[note]]Of course, the opponent can retroactively protect the marine or even [[StableTimeLoop send one back from the future to ensure its own existence]].[[/note]]It should be noted that much of the game is built on these sorts of tactics.** It should also be noted that it's not segregated to the story: you can play with these temporal shenanigans yourself. '''In multiplayer.'''* Averted by ''VideoGame/ChronoTrigger'' in that, while major changes to the timeline (such as the entire plot of killing Lavos) will, of course, have major effects, minor things, such as opening a treasure chest in the past, will, at most, have the effect of making the corresponding treasure chest empty in the future, [[TimeyWimeyBall yet you can get the future chests, then go back in time and open the past ones with no consequence...]] Killing monsters doesn't do a thing; they'll even reappear when you enter the area.** Played straight with Porre, [[FanonDiscontinuity at least if you accept]] ''VideoGame/ChronoCross'' as canon. Remember the small country whose people you told not to be selfish? They [[spoiler:destroy Guardia with the help of [[NotSoHarmlessVillain Dalton]], are implied to have killed Crono and Marle, and gain a strong influence on Zenan]].** Played straight in ''VideoGame/ChronoCross'', although most of it is just [[NiceJobBreakingItHero Serge]]. *** Once you sort through Chrono Cross's labyrinthine plot, it retroactively applies it to Chrono Trigger in a huge way. In a nutshell, [[spoiler: after Crono and friends defeat Lavos and create a good future, Lavos in the past - in an attempt to avert its own destruction - pulls a supercomputer called FATE from the newly created future back in time, to fight with an organic computer that the planet has called in from an alternate future where Lavos never landed on the planet. FATE wins and, in an attempt to make sure that its current existence doesn't prevent its future creation and, thus, create a time paradox, it starts guiding human events to make sure everything happens according to plan. The Lavos that was defeated by Crono, meanwhile, has merged with Schala and formed into a being that is attempting to devour all of spacetime. Schala, for reasons that aren't really clear, winds up altering spacetime herself in order to save an infant Serge from a panther demon, causing Serge to mess up FATE's plan and suddenly become the centrepiece to approximately two dozen people's schemes for saving, destroying, or conquering the world.]] Basically, Crono altering the future by killing Lavos causes a dozen or so beings with the ability to manipulate time to immediately launch into [[GambitPileup an elaborate web of overlapping gambit schemes]] to try and ensure that the new future does or does not come to pass. [[MindScrew And that's the ''short'' version!]]* ''VideoGame/MortalKombat9''. By doing some minor things to avert a BadFuture, Raiden ends up making his and Earthrealm's future doomed. For instance, [[spoiler:preventing Motaro from killing Johnny Cage causes Shao Kahn to kill Shang Tsung and empower Sindel; Sindel subsequently ''slaughters'' nearly all of Earthrealm's warriors.]] Similarly, when Raiden prevents the Lin Kuei from turning Smoke into a cyborg, [[spoiler: they grab Sub-Zero instead.]]* Used for a joke in ''VideoGame/MetalGearSolid3SnakeEater'' where there's a point in the game where you can kill the young version of future turncoat agent Ocelot. Doing so ends the game instantly, with the game telling you that you created a time paradox.** If you do this in the HD Rerelease you also get a trophy stating that all the problems in the series are solved, thus it's over. You still get a Game Over though.* ''VideoGame/TimeSplittersFuturePerfect'' subverts this trope with Cortez causing countless paradoxes and shooting up everything. After all, he is cleaning up the mess of the actual villain. By the end, he manages to destroy the Timesplitters that had made a mess of the timeline, fixing up his own future. It's possible that all his deeds were always meant to happen or were simply erased from existence.* Also subverted in ''VideoGame/Onimusha3DemonSiege''. Samanoske is stuck in present day and can therefore not affect events in the timeline, but Jaques in ancient Japan can and has to due to the Genma mucking around with time travel and causing the current mess in the first place. The two end up being time janitors, in a way.* In ''VideoGame/GhostTrick'', Sissel ''is'' the Butterfly of Doom who can travel back in time and manipulate minor events--and he uses this power to save people rather than to destroy.* Although the ''VideoGame/LegacyOfKain'' series generally runs on YouCantFightFate this trope occurs in Blood Omen when [[spoiler:Kain goes back in time to kill William the Just before he becomes the Nemesis, thereby causing the sequence of events that leads to the genocide of Nosgoth's vampire population by the [[KnightTemplar Sarafan]]. However, the events are not the result of vengeance on the part of the timestream itself but it was precisely calculated by Moebius the Timestreamer.]] * In ''VideoGame/TheJourneymanProject'', the Temporal Security Agency works to prevent this trope from happening, and each Agent - including Gage Blackwood, Agent 5 - is tasked with reversing any changes that some other time traveler would have done to the past. ** Ironically, The TSA made their own change to the past by hiding its Historical Log disc in 200 million BC, though it's lampshaded in that the area it's situated in will inevitably be destroyed by a volcanic eruption.* Used ''VideoGame/StarTrekOnline''. During the "Ghosts" Featured Episode, your character and his team must go back in time to Drozana Station of the 23rd to stop the Devidians from causing havoc with the time stream. One of your crew members will make sure you invoke the Temporal Prime Directive, meaning you can't go around and muck with the time stream all willy-nilly. The first time you go back in time, you don't have much of a choice to muck with the time stream when you end up encounter Dr. [=McCoy=] - saving lives from the Devidians takes priority over everything else and you help pioneer a way to counteract the Devidians' absorptions. The second time, after you destroy a comet the Devidians were using to perform their time travel shenanigans, the Black Ops group you're aiding says they'll make sure everything you've done is kept off the books. ** It's done again in the finale of the Federation's "Klingon War" storyline. You chase Ambassador B'Vat through the Guardian of Forever and learn that his arrival had changed history with the original Enterprise destroyed. You arrived just in time to stop that and you go on to rescue Miral Paris.* The developers of ''VideoGame/UntilDawn'' refer to the mechanic behind the game's branching storyline as the butterfly system, with a butterfly motif appearing in the trailers. And sure enough, given that this is a SurvivalHorror game, some changes can end in doom, making this a case of the ButterflyOfDoom being enacted on ''the player''.* In ''VideoGame/SuperRobotWarsReversal'', Raul and Fiona Graydon attempt to not use this trope when they and their friends are tossed back five years into the past. When they get to a crucial point in history (the GrandFinale of ''Anime/{{Zambot 3}}'' and ''Anime/MobileSuitGundamWingEndlessWaltz''), they suffer a HeroicBSOD before deciding to ScrewDestiny and make sure things happen differently. Things get even worse as you find out that the mechanics found designs of future units such as the Nu Gundam and the Black Serena and have built them five years before they should and allowing you to defeat the BigBad. When you return to their normal time, they learn that their changes brought about ''good'' futures.* ''VideoGame/LifeIsStrange'':** The game features heavy butterfly symbolism: Max gains her time rewinding powers after taking a picture of a blue butterfly, a butterfly icon shows up any time you make an action that will have consequences, and the first episode is titled Chrysalis** The actual trope (seemingly insignificant action causing massive, bad changes in the future) is currently averted, but that may change as more episodes get released and the plot becomes clearer.** This comes into effect in episode 3 when [[spoiler:Max uses her power to save Chloe's dad from dying, rather than create the perfect timeline Max was expecting this instead creates a timeline in which Max is a member of the Vortex Club and is now friends with Victoria, David is now the driver of the school bus, Warren is now dating a girl named Stella and Chloe is now wheelchair bound.]]** This is fully realized at the end of episode 5 when [[spoiler:the tornado from Max's visions hits Arcadia Bay, and Chloe realizes that Max saving her life is what caused the storm destroying the city. Max has to make the choice to either go back to when she took the butterfly picture and not use her power to save Chloe's life, or rip it to shreds and sacrifice Arcadia Bay to keep her best friend/girlfriend alive.]][[/folder]]

[[folder:Web Comics]]* In the now likely defunct webcomic ''WebComic/{{Adventures of John and Dave}}'', Dave goes back in time about three weeks to play a prank on Air Force One and finds that this caused Germany to win UsefulNotes/WorldWarII.* ''Webcomic/SomethingHappens'' has some fun about it [[http://somethinghappens.keenspot.com/d/20070405.html here]].* ''Webcomic/DragonBallMultiverse'': Many of the universes where the villains won are the result of a seemingly minor change in the timelines that snowballed into the heroes losing.** Universes 1 and 10 had the Kaioshin eradicate every threat they found. Freeza being dead, the Saiyans never had a technology or power boost and never became space pirates.** Universe 3 diverged when Bardock put to good use his prophetic visions and managed to take Freeza down, with Saiyans taking over the galaxy, Kakarot never being sent to Earth, and then Raichi taking revenge on the Saiyans. [[spoiler: Piccolo Daimao also fused with Kami, through yet unknown circumstances, with an evil Piccolo being the dominant personality.]]** Universe 4 diverged when Majin Buu opted to quickly absorb Vegeta when he threatened to remove Fat Buu from his cocoon rather than plead with him. Goku is then forced to fight on his own, where he is horribly outclassed; even his Hail-Mary of expending his full power to blow Buu up failed miserably and Buu simply absorbed him as well.** Universe 6 diverged when Goku did not warp back to Earth to save Gohan against Bojack and give him a pep talk.** Universe 7 diverged when all the Nameks decided to fuse into one being to take down Freeza, [[spoiler: losing forever the ability to create Dragonballs in the process]].** Universe 8, where Freeza and his family won, came about because Krilin killed Vegeta on Earth before Goku could stop him. Since Vegeta doesn't show up on Namek, he's not around to provide an extra distraction to Freeza or his henchmen, which eventually culminates in Freeza killing everyone on Namek (except Goku, which remained alive to destroy Freeza's capital).** Universe 13, where Kakarot never hit his head and thus never lost his Saiyan mentality. So, instead of him becoming the cheerful and kindhearted man in canon, he becomes a ruthless killer who is more than a little mentally unbalanced. It goes without saying that humanity isn't around in U13 anymore.** Universe 14 diverged when Trunks never came back to the future after his U17 counterpart got killed by Cell, thus ensuring the cyborgs could have free reign.** Universe 16 diverged when Vegito made the choice to not remove his shield aura effect when inside Boo, and remained fused forever, freeing everyone and destroying Kid Boo before he could destroy the Earth. Also, Enma did not listen to his request to reincarnate him into Oob, so in this universe there is no Boo.** Universe 17 diverged when Vegeta did not strike Cell in the back and distract him. This allowed Cell to overpower SSJ2 Gohan.** Universe 19 diverged when Raditz killed Goku on Earth, according to the french novelization. This led to them attacking Helior with reduced numbers, and Helior probably weathered the assault, and stepped up their game.** Universe 20 diverged when Broly survived his second coming, after being thrown into space by the heroes, and did not burn in the Sun.[[/folder]]

[[folder:Web Original]]* The Alternate History Forum, home of ''Literature/LookToTheWest'' and ''Literature/DecadesOfDarkness'' among others, is divided on the issue. There are purists ("step on a butterfly and everything changes") and non-purists ("consequences of an event ought to follow on logically: things take a while to change, and sequences of reasons can be made"). People who don't include ''any'' "ripple" of changes are laughed at. To quote veteran member Jared "In 1618, Australia will be discovered on time and the effects [of a sedentary yam-farming aboriginal civilization] will spread. Anyone asking "Great! How does this changed Australia affect World War 2?" will be fed to the blobfish."** This is parodied in ''Literature/{{Reds}}'', where the alternate history version of the Alternate History Forum appears, and the members discuss the alternate timeline... and the exact same kinds of arguments crop up.** However, a key general note: the 'of doom' aspect is avoided in all but deliberately dystopic timelines (things change, often without directly described causal relations to the original point of divergence -- but the changed things are often a mix of good and bad).* Played with, and ultimately subverted, in ''Machinima/RedVsBlue'': Church gets transported a thousand years into the past and then uses the time to come up with plans to prevent the accident that caused him to travel through time in the first place. The loop repeats dozens of times but everything he tries never changes anything. [[spoiler: This is due to the fact that he never traveled through time at all, but merely believed he was doing so because the AI Gamma was deliberately torturing him and trying to drive him through despair via a simulation.]]%%* [[http://www.youtube.com/watch?v=BaxBFnIUTrc This]] video is this trope in a nutshell. * The sixth season of ''SonicForHire'' involves the Butterfly Effect. Some examples include there not being such of a thing as sliced bread, but it is called "chopped with your hands bread" instead.[[/folder]]

[[folder:Western Animation]]* ''WesternAnimation/TimeSquad'': Planet of the Flies, a {{parody}} of ''Film/{{Planet of the Apes|1968}}''. Tudrussel squashes a fly in the Stone Age, altering history so that the world is ruled by giant flies. Complete with a ruined Statue of Liberty scene. "You maniacs! You blew it all up!"* ''WesternAnimation/PhineasAndFerb'': "Phineas and Ferb's Quantum Boogaloo" featured an adult Candace going back in time to bust Phineas and Ferb for the rollercoaster and returning to her own time to learn it was now a BadFuture. As it turns out, her effort to bust her brothers not only created a wave of child-proofing hysteria, but it caused Perry the Platypus to get injured by Dr. Doofenshmirtz's evil scheme backfiring, instead of Doofenshmirtz like in the original timeline. This allowed Doofenshmirtz to ride the wave of hysteria and take over the Tri-State Area, turning it into a ruined industrial dystopia where fun and creativity are outlawed, kids are kept in PeopleJars until they reach adulthood, and [[ArsonMurderAndJaywalking everyone is forced to change their name to "Joe"]].* In the ''[[WesternAnimation/TheSimpsons Simpsons]]'' WesternAnimation/TreehouseOfHorror segment "Time and Punishment", [[MakesJustAsMuchSenseInContext a malfunctioning toaster]] transports Homer to the prehistoric past. He remembers some advice Grandpa gave him regarding [[LampshadeHanging this very trope]], then [[IgnoredEpiphany instantly forgets it]] to squash a bug. When he returns to the present, [[CrapsaccharineWorld Flanders has taken over the world]]. His attempts to fix the timeline cause alternate futures that range from even worse to just plain weird. When one of his sneezes causes all of the dinosaurs to drop dead, he moans, "This is gonna cost me." Homer eventually snaps and just starts whacking everything with a baseball bat, creating a future that's actually pretty near normal, except everyone has weird, elongated, lizard-like tongues.-->'''Homer:''' ... ''(shrugging)'' Eh, close enough.** One of the alternate futures seems perfect for him: his sisters-in-laws are dead, his family is rich, the children are polite… but then he learns that donuts apparently don't exist in this timeline when he uses the word and nobody knows what he's talking about. He disappears into the past to try again, before we see that it ''rains'' donuts in this future.*** Ironically, this future is the result of the aforementioned sneezing on the dinosaurs.* In ''WesternAnimation/{{Futurama}}'''s [[TheMovie first movie]], "Bender's Big Score", time travel plays a huge role in the plot. There's even mention of a failsafe in the universe itself that erases impossibilities created by time travel, like the same person meeting themselves, that prevents the Butterfly effect from having a dangerous effect. It comes up again in an episode where the Professor makes a time machine that only travels forward in time [[spoiler:resulting in seeing the big bang twice as the universe resets itself and squashing the current timeline versions of themselves, stopping a paradox]].** In "Roswell That Ends Well", they go back in time to ''become'' the Roswell Incident. When Professor Farnsworth finds out that Fry's grandfather is there he gives him the classic advice for people going back in time: "Don't do anything that will change history. Unless, you're ''supposed'' to do it, in which case, for the love of God, don't ''not'' do it." Of course he does by killing his grandfather but the effects are minimal because [[spoiler:he realizes that he is not vanishing, so his grandfather can't really be his ancestor. However, he takes the extra step of thinking this disqualifies his grandmother from being his grandmother and sleeps with her, inadvertently ''becoming'' his own grandfather]]. Farnsworth gets fed up after this incident and decides to just attack Roswell and steal their ship back. "Screw history! Let's just get the hell out of here!" When that plan actually ''works'', the Professor triumphantly shouts "Choke on THAT, causality!" * The ''WesternAnimation/InvaderZim'' episode "Bad, Bad Rubber Piggy" starts out with Professor Membrane explaining on his show that, as tempting as it sounds, purposely changing the past would create more problems than it solves (Such as a giant fish in a bear-suit rampaging). Zim, of course, plans to do just that to get rid of Dib, but his attempts to destroy Dib's younger self eventually go from 'make him more decrepit' to 'gives him more super weapons from the professor.'* In the ''WesternAnimation/LiloAndStitchTheSeries'' episode "Melty", the duo use Jumba's time machine to attempt to simultaneously capture the experiment and impress Lilo's crush Keoni, but after experimenting different methods it becomes apparent that each iteration causes something to go horribly wrong, often by setting off a {{Rube Goldberg|Device}}-esque chain of events (one involving an actual butterfly). In one case, they accidentally go forward instead and are met by an apocalyptic world directly stemming from their actions on that day.* Invoked in a ''WesternAnimation/RobotChicken'' episode when a kid says that a butterfly's wings flapping can cause storms etc. The other kid smashes the butterfly, causing an earthquake in Japan. The geisha quickly steps on another butterfly, causing an erupting volcano which melts one of the kids. The remaining kid [[RuleOfThree rips a third butterfly in half]], and Franchise/{{Godzilla}} appears to burn the geisha's house.* In the episode "Sword of Righteousness", WesternAnimation/EarthwormJim uses said sword to go back in time and shave UsefulNotes/AbrahamLincoln's beard at the Gettysburg Adress ("Well, that's a big goodbye to my credibility.") to see if his face on the penny will change. When he gets back, he finds Peter Puppy dressed like Colonel Sanders:-->'''Alt-Peter:''' What are y'all doin' now, Earthworm Bubba?\\'''Jim:''' ''[sheepish]'' I think the training is going well...aside from changing the course of history and all...\\'''Sword:''' Listen to me! You will go and put Lincoln's beard back! And then no more time-travel for you, young worm!* Brian in ''WesternAnimation/FamilyGuy'' goes back several years in time with Stewie to see where he had buried a ball. Stewie warns Brian not to touch anything or to talk to anyone, for doing so could alter their present time. Once the duo returns to their original time, Stewie discovers that Brian had told his past self about the September 11th terrorist attacks, which caused his past self to stop the attacks from ever happening. Sounds good, right? Sure, the lives of 3000+ people were saved, but the action caused George W. Bush to lose his reelection for U.S. President in 2004, which motivates him to have all the southern states secede from the rest of the country and declare a second civil war, but with nukes being used and causing the death of over a ''million'' people. Whoops.* In the ''WesternAnimation/MyLittlePonyFriendshipIsMagic'' season 5 two-part finale "The Cutie Remark", Starlight Glimmer, in a fit of rage over the Mane Six breaking up her village of "equality", enacts a time travel spell to prevent Rainbow Dash's first Sonic Rainboom, preventing the Mane Six from gaining their Cutie Marks at that point and creating their future bonds. Twilight constantly goes back to stop her, but each time she does so, it just creates a worse and worse future - One where King Sombra conquers Equestria, one with the Changelings in charge, then Nightmare Moon, Tirek, Discord, ''[[ArsonMurderAndJaywalking the Flim Flam Brothers]]'', then ultimately nothing but a barren wasteland. Twilight ends up dragging Starlight into this last timeline to show her what she's doing. [[VillainousBreakdown She doesn't take it well.]]* Invoked in one episode of ''WesternAnimation/DarkwingDuck'' where Darkwing and Gosalyn accidentally travel back to when Darkwing was a kid. Gosalyn tells Darkwing not to interfere in the past, so Darkwing leaves rather than stop the King, an Elvis-themed villain with a shock-wave guitar, from committing a robbery. Then it gets inverted where ''not'' interfering in the past is what causes the present to change, creating a world where the King rules the city. Thus, Darkwing and Gosalyn have to go back to the past in a rare occurrence where SetRightWhatOnceWentWrong meets YouAlreadyChangedThePast (with a dash of StableTimeLoop as Darkwing inspired his younger self to become a hero).* In one episode of ''WesternAnimation/FairlyOddParents'', Timmy accidentally melts his father's sports trophy, so he [[SarcasmMode does the logical thing]] and... goes back in time and prevents his father from winning the trophy in the first place. This creates a BadFuture in which Timmy's dad is a Big Brother-esque dictator who enforces happiness on the population and has a major complex about the lost trophy. Timmy goes back and fixes the mess by winning the trophy in his father's stead, and everything returns to normal except that [[ItMakesSenseInContext Timmy and the Internet have swapped names]].** In another episode, Timmy travels back to March 15, 1972 to try and prevent the incident that turned Denzel Crocker in the fairy-obsessed miser he is today. [[NiceJobBreakingItHero Timmy instead ends up]] ''[[NiceJobBreakingItHero causing]]'' [[NiceJobBreakingItHero said incident]], and is then banned from ever returning to March 1972. In the process, he also somehow causes George [=McGovern=] to win the 1972 presidential election, as he's then warned against interfering with said election win despite having caused it in the first place.* In ''WesternAnimation/XiaolinShowdown'' Omi decides to use the Sands of Time hoping that he can save Chase Young from being turned evil by Hannibal Bean. In doing so, however, Hannibal turns Master Monk Guan instead, and not only is Master Monk Guan shown to be even more dangerous on the Haylin side than Chase Young (forcing the monks out of the temple and trapping Master Fung in the Ying Yang world), [[TheDragon but he's shown to be completely loyal to Hannibal]].* Referenced by Cyborg in ''WesternAnimation/TeenTitans'' as the page quote shows, and he intends to remain in his exact position and not touch anything...until he sees he's literally [[OhCrap standing in-between]] two [[OnrushingArmy OnrushingArmies]]. The ending implies it was a StableTimeLoop all along. [[/folder]]----